Multi-service packet network interface

ABSTRACT

An integrated circuit device for use in providing packet service via multiple lower speed communications links and methods of operation of same is disclosed. The device may be capable of supporting Ethernet packet network service using a bonded group of time division multiplex or digital subscriber loop communications links by distributing the data traffic over the individual connections in the group. An embodiment of the invention may also include SONET/SDH compatible optical carrier framing, cross connect, and packet mapping functionality. It may include a telecom bus compatible interface for the connection of additional communications devices, and may incorporate an M13 multiplexer to permit the merging of multiple DS1 data streams into a single DS3 data stream. An embedded microprocessor core and embedded memory may permit an embodiment to support enhanced remote diagnostic, trouble reporting, traffic management, and software update capabilities.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

[0001] The applicants claim priority based on provisional applicationSer. No. 60/419,865, “Multi-Service Ethernet-Over-SONET SiliconPlatform,” filed Oct. 21, 2002, the complete subject matter of which isincorporated herein by reference in its entirety.

[0002] This application is a continuation in part of U.S. applicationSer. No. 10/318,444, “Multi-Service Ethernet-Over-SONET SiliconPlatform,” filed on Dec. 13, 2002, which is incorporated herein byreference in its entirety.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0003] [Not Applicable]

MICROFICHE/COPYRIGHT REFERENCE

[0004] [Not Applicable]

BACKGROUND OF THE INVENTION

[0005] Certain embodiments of the present invention relate to providingaccess to broadband communication systems. More specifically, certainembodiments relate to an apparatus which provides an interface toconnect to broadband synchronous optical networks in order to provide avariety of synchronous and packet network connections. Additionalembodiments described relate to an apparatus that may provide a packetnetwork interface operating at a higher bit rate using a group ofcommunications links operating at a lower bit rate as the transportmechanism.

[0006] In the past, a variety of transmission technologies have beenused to electronically transfer large amounts of digital information,including both terrestrial and satellite links. Terrestrial facilitiesthat have commonly been used include both buried and above-ground cable,microwave radio and most recently, optical fiber, which offers thelargest bandwidth. Networks used for such high capacity data transportsystems are typically synchronous networks.

[0007] A synchronous network is one example of what is traditionallyreferred to as a circuit-switched network. In a synchronous network,data is transmitted from one location to another as a continuous streamof digital information moving from the source to the destination at aconstant rate. The stream is organized as a sequence of frames, eachframe containing a fixed number of fields in a defined order, each fieldof the same length. An end-to-end connection or “circuit” in asynchronous network exists as a collection of individual segments whichare assigned when the circuit is built or “provisioned.” At the timethat a circuit is provisioned it is assigned the use of one or more ofthe fields in the frames exchanged across a given segment, and a circuitmay be assigned a different field within the frames carried on differentsegments. The transfer of data at the point of connection of one segmentto another is time synchronized, and does not add significant delay.Because the data on any segment moves at a constant rate, and no delayoccurs at the connections between segments, the time needed to travelfrom one end to the other end of a circuit is fixed. The SynchronousOptical Network (SONET) and Synchronous Digital Hierarchy (SDH) are theprincipal synchronous optical network standards currently in use. In theSONET standard, the term “circuit” in the above discussion correspondsto the SONET term “path,” and the term “segment” corresponds to theSONET term “link.” An example of a path in a SONET network is shown inFIG. 1.

[0008] In most cases, no single user needs all of the capacity of anoptical fiber-based transmission system, so the standards have beendesigned to provide a means to share the bandwidth. For example, SONETnetworks typically operate at data rates of between 51.84 megabits persecond (Mbps) and 10 gigabits per second (Gbps). Within that range, adevice called an add/drop multiplexer (ADM) can be used to insert orextract a lower bit rate stream to or from one of a higher bit rate. Adiagram showing the SONET hierarchy and the relationships between bitsrates is illustrated in FIG. 2.

[0009] In contrast to circuit switched networks, packet networks consistof a mesh of nodes interconnected by links, and data is exchanged inbursts called packets. The use of packet networks is growing inpopularity due to the flexibility offered by the ability of a packetnetwork to efficiently handle multiple data streams of widely varyingbandwidth. This flexibility is one of the factors helping to bring abouta convergence of data and voice networks. The packet contents includethe address of its destination, and it is the function of each node todirect each packet that it receives to a link that will send it closerto its destination. In general, a packet is queued at a node beforebeing forwarded to the next node in the path, because it may have towait for the outgoing link to become available. Packets may containvoice, data, or video information, and can be of varying length. Theamount of time that a packet takes to travel from the source to thedestination varies based upon a number of factors including the numberof nodes, the speed of the links, and the queuing delay that occurred ateach node. Each of the services supported on a packet network has itsown set of requirements including, for example, end-to-end delay, packetloss, and privacy. Designers of packet networks take those requirementsinto consideration.

[0010] Synchronous optical networks are the primary transport mechanismfor long distance transmission of information, and are becomingincreasingly important in metropolitan areas. At the same time, the useof packet networks is growing rapidly due to their ability toefficiently carry multiple data streams of widely varying bandwidth.With the passage of time, the number and variety of data services, thenumber of users, and the total bandwidth required at any particular userlocation will grow. Some legacy equipment requires lower speedsynchronous network connections, while other equipment requires a packetnetwork interface. In some applications, more than one synchronousoptical link may be needed to support the total bandwidth required. Asuser demand for higher bandwidth connections grows and synchronousoptical networks expand, support for connections of varying bandwidthwill become increasingly important. The result is an ever-growing needfor high-capacity, highly-functional, cost-effective systems for theconnection of synchronous optical networks to packet networks and tolower speed synchronous networks.

[0011] The functionality that may be needed to connect a SONET or SDHsynchronous optical network and a packet network includes that of anAdd-Drop Multiplexer (ADM) or terminal, a Digital Cross-Connect (DCC),and a Multi-Service Provisioning Platform (MSPP). ADMs are used totransport SONET or SDH traffic on network ring topologies. An example ofsuch a SONET ring is shown in FIG. 3. The most popular of these ringtopologies are Unidirectional Protected Switched Rings (UPSR) andBidirectional Line Switched Rings (BLSR). In this arrangement, the nodeson the ring are linked by two optical fiber connections that transmitdata in opposite directions. Should one of the optical fibers experiencea failure, the nodes in the ring are still able to communicate using theother optical fiber. The ADMs are nodes on such rings that are used toarbitrate (add or drop) traffic to or from the ring. Rings areinterconnected by gateways, as illustrated in FIG. 4. The client trafficon the ADM (the traffic that is added or dropped from the network ring)is normally transmitted at a lesser data rate than the network traffic(the traffic on the ring). Typical ring traffic rates for both SONET andSDH are 155 Mbps, 622 Mbps, 2488 Mbps and 9953 Mbps. These correspond toOC-3, OC-12, OC-48 and OC-192 rates for SONET respectively, and toSTM-1, STM-4, STM-16 and STM-64 rates for SDH respectively. Clienttraffic on the ADM can either be a lower SONET or SDH rate than the ringrate, or it can be a PDH rate (Plesiochronous Digital Hierarchy), suchas DS1, DS2 or DS3 or E1, E2 and E3. The DS1 rate is 1.544 Mbps, DS2 is6.312 Mbps, DS3 is 44.736 Mbps, E1 is 2.048 Mbps, E2 is 8.448 Mbps, andE3 is 34.368 Mbps.

[0012] A SONET/SDH terminal performs a function similar to that of anADM except that the network connection is not in a ring configuration. Aterminal terminates a high speed point-to-point SONET path, and handsoff a number of lower rate lines and paths on the client side. Forexample, an OC-3 terminal could be used to terminate an OC-3 path andhand off three DS3 lines on the client side.

[0013] The DCCs are used to switch and groom traffic between differentlines and paths. A network may include several ADMs and terminals toarbitrate or terminate traffic along rings or point-to-pointconnections, and a DCC will be used to switch the traffic between allthe paths. A DCC is a circuit switch, which means that all connectionsare provisioned statically.

[0014] The Multi-Service Provisioning platform combines the function ofthe DCC, the ADM, and the terminal along with the ability to supportdata protocols such as Ethernet to the client users. In all instancestoday, these MSPPs are scalable platforms based on a chassis. This meansthat to build a useful system, a user needs to install a specificcircuit card supporting each function. The purpose of the chassis is tohold the required circuit cards, provide an electrical interconnect or“backplane” to connect signals from one card to another, and to supplypower for system operation. For example, separate cards are needed forswitching, supporting the ADM function, supporting and mapping DS1traffic, supporting and mapping DS3 traffic, and supporting and mappingEthernet traffic. FIG. 5 illustrates an example chassis arrangement ofan MSPP 500, showing Ethernet interface card 502, cross-point switchcard 504, synchronous optical interface cards 506 and 508, and processorcard 510. The silicon devices developed to support these platforms tendto implement an ever increasing but still small portion of the neededfunctionality. For instance, there are devices on the market supportingSONET framing, DS1 framing and mapping, DS3 framing and mapping, DS1mapping into DS3 (known as M13 mappers), Ethernet-over-SONET mappers,and digital cross-connects. Building a system is complex and costly dueto the number of cards and/or individual integrated circuit devicesrequired. The variety and number of network connections that can besupported by the MSPP system is limited by several factors, includingthe level of functionality and number of connections on each integratedcircuit device, the number of circuit cards that can be contained withinthe chassis, and the number of signals that must be carried by thebackplane.

[0015] Situations exist where Ethernet packet network service is desiredand where optical connectivity is not available or is not costeffective, but where there are available multiple lower bit-ratecircuit-switched communications links. For example, synchronous timedivision multiplex service such as DS1 has been in widespread use formany years. Some subscribers may have multiple DS1 or digital subscriberloop (DSL) lines available on site, but have a need for 10 Mbps Ethernetpacket connectivity. Many subscribers that may need Ethernet packetnetwork connectivity cannot make effective use of even the lowest levelof SONET/SDH capacity. A low-cost solution to provide a packet networkinterface via multiple lower speed links is needed.

[0016] As can be seen from the above discussion, there is a fundamentaldisconnect between the packet network environment and core opticalnetworks such as SONET and SDH. There is also a need for systems able toprovide packet network connectivity using available lower speedfacilities. The relatively high cost of the technology typically used tofill these gaps hinders network growth and further expansion of supportfor metropolitan optical networks and packet network service.Accordingly there is a need for a more compact, cost-effective, and moreflexible solution to providing packet network over legacy facilities aswell as newer SONET and SDH-based optical networks.

[0017] Further limitations and disadvantages of conventional andtraditional approaches will become apparent to one of skill in the art,through comparison of such systems with some aspects of the presentinvention as set forth in the remainder of the present application withreference to the drawings.

BRIEF SUMMARY OF THE INVENTION

[0018] Aspects of the present invention relate to a device that permitsthe interconnection of circuit-switched and packet networks. Morespecifically, one embodiment of the present invention may be a singleintegrated circuit that includes the functionality that may be requiredto provide Ethernet packet service using a group of lower-speed, timedivision multiplex connections.

[0019] An embodiment in accordance with the present invention maycomprise a hashing processor for selecting a transmit data channel andfor designating a receive packet interface and a transmit packetinterface. In addition, it may comprise a packet mapper for processingat least one transmit packet from the designated transmit packetinterface operating at a first bit rate, the packet mapper transferringthe contents of the at least one transmit packet to the selectedtransmit data channel, and may process data from at least one receivedata channel, producing at least one receive packet for transmission onthe designated receive packet interface operating at the first bit rate.Further, it may comprise at least one communication interface forserializing data from the transmit data channel to form a transmit datastream, and for passing to the receive data channel data deserializedfrom a receive data stream, the transmit data stream and receive datastream operating at a second bit rate. A packet format of the at leastone receive packet and the at least one transmit packet may be compliantwith at least one of the Institute of Electrical and ElectronicEngineers 802.3 family of Ethernet standards. In such an embodiment, thefirst bit rate may be greater than the second bit rate.

[0020] An embodiment may also comprise at least one optical carrierframer for performing transmit framing on data from at least onetransmit data channel producing a transmit data sequence, and forperforming receive framing on a receive data sequence producing data forat least one receive data channel. The packet mapper may be compatiblewith the American National Standards Institute T1X1.5 Generic FramingProcedure, the International Telecommunications Union X.86 Ethernet overSONET recommendation, or the Internet Engineering Task Force RFC 1662point-to-point protocol specification. In addition, a format of thetransmit data sequence and the receive data sequence may be compatiblewith the Synchronous Optical Network or Synchronous Digital Hierarchyoptical carrier standard.

[0021] Another embodiment of the present invention may comprise a businterface for connecting additional communications interface deviceswhere the bus interface is a telecom bus compatible interface. The atleast one communication interface of an embodiment may comprise at leastone T/E carrier framer for receiving and transmitting data in timedivision multiplexed format which may comprise a DS1 or E1 format framerand a DS3 or E3 format framer. It may further comprise an M13multiplexer for converting DS1 format time division multiplex datastreams to and from DS3 format.

[0022] A further embodiment in accordance with the present invention maycomprise at least one embedded microprocessor core arranged in order toreceive signals from the hashing processor, and an embedded memory forstoring information to be accessed by the at least one embeddedmicroprocessor core. It may comprise an external memory interfacearranged to allow the at least one embedded microprocessor core toaccess information stored in an external memory device, and thefunctionality of the embodiment may be contained within a singleintegrated circuit.

[0023] Another aspect of the present invention is a method of operatinga data communication device, the method comprising receiving a firstpacket from a first packet stream at a higher bit rate, selecting afirst data link from a predefined group of data links, depacketizing thefirst packet to a first data stream, transmitting the first data streamon the first data link at a lower bit rate, receiving a second datastream on a second data link at the lower bit rate, packetizing thesecond data stream into a second packet, designating a second packetstream on which to send the second packet, and transmitting the secondpacket on the second packet stream at the higher bit rate. A packetformat of the first packet stream and the second packet stream may becompliant with at least one of the Institute of Electrical andElectronic Engineers 802.3 family of Ethernet standards. The first datalink and the second data link may use a time division multiplex formatwhere the time division multiplex format is DS1 or E1 compliant. Thefirst data link and the second data link may also be a type of digitalsubscriber line.

[0024] Another aspect of the invention may include machine-readablestorage, having stored thereon a computer program having a plurality ofcode sections executable by a machine for causing the machine to performthe foregoing.

[0025] These and other advantages, aspects, and novel features of thepresent invention, as well as details of illustrated embodiments,thereof, will be more fully understood from the following descriptionand drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

[0026]FIG. 1 is a block diagram showing the elements along the path in aSONET network.

[0027]FIG. 2 is a hierarchy diagram showing the names and relationshipsof the various link capacities available within the SONET hierarchy.

[0028]FIG. 3 is a block diagram showing the structure of a exemplarySONET ring, and the elements and interconnections that may be present.

[0029]FIG. 4 is a block diagram illustrating an exemplaryinterconnection of two SONET ring structures, and the gateway whichconnects them.

[0030]FIG. 5 is an illustration of the chassis of an exemplarymulti-service provisioning platform, showing the arrangement of theindividual circuit cards that may be used to support variouscommunications services.

[0031]FIG. 6 is network diagram showing an exemplary networkconfiguration in which a SONET network and a packet network areinterconnected to provide a variety of services, in accordance with anembodiment of the present invention.

[0032]FIG. 7 is a high-level block diagram illustrating a single-chipembodiment of the present invention.

[0033]FIG. 7a shows an embodiment of the present invention which iscontained within one or more integrated circuits on a single circuitcard having a single connector.

[0034]FIG. 7b illustrates an embodiment in accordance with the presentinvention where the functionality shown in FIG. 7 is incorporated on asingle circuit card having two connectors.

[0035]FIG. 8 is a block diagram showing functionality that may bepresent in one embodiment according to the present invention.

[0036]FIG. 8a shows an exemplary embodiment illustrating the bonding ofseven DS1 synchronous time division multiplex circuits into a bondedgroup that transports the traffic from a first 10 Mbps Ethernet link toa second 10 Mbps Ethernet link, in accordance with the presentinvention.

[0037]FIG. 8b is a block diagram showing functionality that supports theuse of bonded links in an embodiment of the present invention.

[0038]FIG. 9 is a high-level flow diagram showing a method of operatingan embodiment of the present invention.

[0039]FIG. 9a is a high-level flow diagram illustrating a method ofoperating another embodiment in accordance with the present invention.

[0040]FIG. 9b illustrates a network architecture in which two bondedgroups are used in sequence, in accordance with the present invention.

[0041]FIG. 9c shows an exemplary network architecture using multipleembodiments of the present invention to interface a packet link to aSONET optical link.

[0042]FIG. 10 is a high-level flow diagram showing another method ofoperating an embodiment in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0043] Aspects of the present invention may be seen in FIG. 6, whichillustrates the interconnections in an example of a data communicationsnetwork. As shown in the diagram, portions of the network, such as SONEToptical link 606, metropolitan area network connection 616, and SONETADM Network 602, are synchronous optical network links. Other portions,such as packet connection 618 linking ADM 608 to users 614, and Core IPNetwork and Public Internet 604, are constructed using a packet network.The fundamental difference in these two forms of data transport mayrequire a means at several points along the transmission path to adaptpacketized data for transmission via a synchronous link, and synchronousdata for packet transport. For example, packet data traffic from serviceprovider 620 destined for users 612 may be sent in Ethernet packetformat from service provider 620 through Core IP Network 604 anddirected onto packet-over-SONET link 606. The broadband traffic may thenpass through SONET ADM Network 602 onto metropolitan area network 616 tomulti-service provisioning platform 610, where it would be mapped intoone or more Ethernet packet connections to users 612. Packets flowingfrom users 612 back to service provider 620 would require similar dataformat adjustments. An embodiment of the present invention may providethe functionality needed to allow a broadband synchronous opticalnetwork to serve a variety of synchronous and packet network connectionsin a flexible manner at lower cost than existing alternatives, and maybe incorporated into a circuit card in add/drop multiplexer 608. It mayalso be used to offer Ethernet services in metropolitan markets byleveraging the SONET infrastructure. To support such an application, anembodiment of the present invention may be contained withinmulti-service provisioning platform 610. In such applications, it maysupport the use of Ethernet private lines, and advanced Internetprotocol (IP) services such as Voice-over-IP (VoIP) telephony. Thepresent invention may also be used to provide advanced remotetroubleshooting features on subscriber connections 618.

[0044] An embodiment of the present invention may combine all of thefunctionality that may be needed to provide client-side support for avariety of interfaces, including 10 Mbps/100 Mbps and gigabit Ethernet,DS1/E1 and DS3/E3 time-division-multiplexed synchronous links, andnetwork or trunk-side interfaces for one or more synchronous opticallinks or DS3/E3 time-division-multiplexed synchronous links in a singleintegrated circuit, or in a multi-chip configuration. A high-level blockdiagram illustrating an exemplary embodiment of the present invention isshown in FIG. 7. In this embodiment, incoming signals from SONET line704 are converted by SONET-to-Ethernet/TDM Conversion block 710 into oneor more packet streams 725 and one or more TDM data streams 730. In thereverse direction, the functionality of Ethernet/TDM-to-SONET Conversionblock 720 receives one or more packet streams 735 and one or more TDMdata streams 740, and converts them into a format suitable fortransmission via SONET line 715. The functionality shown in FIG. 7 forinclusion in an embodiment of the present invention permits therealization of a single-chip device. For example, it is possible toeliminate the Optical Internetworking Forum System Packet Interface(SPI) typically used to interconnect some of the illustratedfunctionality. Removing the need for this interface not only frees thechip area that would typically be used for the interface components, itenables an embodiment of the present invention to incorporate asignificantly larger number of virtual channel connections between thepacket processing and network interface (SONET/TDM) blocks. Thisincreases device capacity and performance, and permits the integrationof the functionality of FIG. 7 into a single integrated circuit deviceor a multi-chip solution of lower cost and higher performance than priorart solutions.

[0045]FIG. 7a shows an embodiment of the present invention in which theabove functionality is contained within one or more integrated circuitson a single circuit card 705 a. In such an embodiment, both the SONETand packet data streams are directed through a single connector 715 a.The high level of functionality present on circuit card 705 a eliminatesthe need for many other circuit cards in the MSPP 500 of FIG. 5, freeingcard slots for additional circuit cards 705 a, or for the inclusion ofother functionality in MSPP 500. FIG. 7b illustrates another embodimentin accordance with the present invention where the functionality shownin FIG. 7 is incorporated on a single circuit card 705 b having twoconnectors. Connector 715 b may, for example, carry SONET receive andtransmit signals 710 b and 720 b, respectively. Connector 725 b may, forexample, carry Ethernet receive and transmit signals 730 b and 740 b,respectively, and time division multiplex receive and transmit signals750 b and 760 b, respectively. Such an embodiment eliminates the needfor the backplane typically present in systems with this level offunctionality, and permits the development of a relatively small,SONET-to-Ethernet interface device. Additional details of thefunctionality that may be present in embodiments such as these follows.

[0046]FIG. 8 shows a block diagram illustrating further detail offunctionality that may be present in a single-chip embodiment accordingto the present invention. Such an embodiment may incorporate achannelized framer 802, which may support the Synchronous OpticalNetwork (SONET) and Synchronous Digital Hierarchy (SDH) protocolspecifications of optical link 834. The incoming and outgoing paths ofoptical link 834 of FIG. 8 correspond to, for example, optical links 704and 715 of FIG. 7, respectively. Channelized framer 802 may supportUni-directional Protected Switched Rings (UPSR) with protected ADMuplinks via OC-12/48 optical lines. In such an arrangement, automaticprotection switching (APS) control 820 supports switching from the mainto the protection line. An embodiment may also support a Bi-directionalLine Switched Ring (BLSR) ring topology. Channelized framer 802 mayincorporate a full-capacity, non-blocking Synchronous Transport Signal(STS)/Synchronous Transport Module (STM) and Virtual Tributary(VT)/Tributary Unit (TU) cross-connect which may be used to switchchannelized data streams between the optical line 834 and packet mapper804, subscriber-side DS1/E1 and DS3/E3 framers 814 and 816, and telecombus interface 822. An embodiment may support complete line and pathoverhead processing, including full STS/STM and VT/TU pointerprocessing. In addition, an embodiment may interface with atime-division-multiplexed (TDM) DS3/E3 uplink 836 via DS3/E3 framer 818.

[0047] Packet mapper 804 may support virtual concatenation (VC) forcompatibility with the installed SONET/SDH network infrastructure, andmay enable the use of various traffic segregation methods, for example,stacked virtual local area networks (VLANs), multi-protocol labelswitching (MPLS) labels, and VT1.5 and/or STS-1 Ethernet-over-SONET(EoS) mapping. Mapping of VLAN/MPLS groups to create a link-layer tunnelthat may be supported by VLAN Engine 808. The use of provisioned tunnelswith MPLS or VLANs may ensure that the bandwidth provisioned forsubscriber access to Internet Protocol (IP) services is maintained, andthat high-priority traffic will have the bandwidth resources needed tobe passed unconstrained through the network during times of congestion &restoration. In one embodiment, packet mapper 804 may support Ethernetmapping to SONET using, for example, the ANSI T1X1.5 Generic FramingProcedure (GFP), the ITU X.86 EoS recommendation, or the InternetEngineering Task Force (IETF) RFC 1662 point-to-point protocol (PPP)specification. These procedures may be used for the Ethernet-to-SONETmapping functions, while 802.3x may be used for flow control at asubscriber line interface. Internet access traffic may be mapped into ashared concatenated channel, and both high order (STS-1-Xv) and loworder (VT1.5-Xv) virtual concatenation may be supported. This capabilitymay enable mapping to a channel of any size with 1.5 Mbps granularity.Each subscriber channel may be mapped to its own SONET channel. Thesubscriber may have multiple channels per physical port, for example, aprivate line channel and a channel for Internet access, and may alsohave multiple private lines on the same port. VLAN/MPLS tags may bemapped to physical ports, via media access control (MAC) addresses aswell as logical channels.

[0048] Ethernet service on packet links 830 may be 10 megabit per second(Mbps), 100 Mbps, or 1000 Mbps. (gigabit) Ethernet (GigE/GbE)connections which may be supported by 10 Mbps/100 Mbps MAC 810 and Gig-EMAC 812. Both MAC 810 and MAC 812 may connect to external physical layer(PHY) interface devices (not shown). Support for TDM DS1/E1 and DS3/E3interfaces may be provided by DS1/E1 framer 814 and DS3/E3 framer 816via synchronous connections 832, the specifications of which may bedesigned to interface with appropriate external physical interfacedevices (not shown). An embodiment may allow the connection ofadditional communications interfaces such as additional DS1/E1 or DS3/E3framers, through the use of telecom bus interface 822. The presentinvention may support full duplex operation at full rate for all framesizes for 10BaseT, 100BaseTX, 1000BaseLX/SX. For telephone gradesubscriber loop cabling, an Ethernet-to-DSL bridging chip may be used.

[0049] An embodiment of the present invention may support services suchas Ethernet Private Lines, which provide secure local area network (LAN)interconnections between corporate sites, Internet access over Ethernetphysical service links, and packet voice. An embodiment of the presentinvention may provide support for delay-sensitive traffic, such as IPtelephony over Ethernet, which generally requires guaranteed minimumlatency. IP-based interoffice telephony allows a single access line fordata & interoffice voice, permitting cheaper interoffice voice callsusing the IP network. This also allows re-use of an existing privatebranch exchange (PBX) infrastructure. Access to the public switchedtelephone network (PSTN) may be possible via a service provider'sgateway. In such an arrangement, the subscriber pays only for dataaccess service.

[0050] An embodiment of the present invention may support Ethernetprivate line service, which provides point-to-point transparenttransport using Ethernet. Private line service implies that allattributes of the subscriber's Ethernet channel are preserved throughoutthe transport network, e.g. VLANs, etc. This capability allows asubscriber to connect two corporate LANs together, leveraging the SONETinvestment by making use of SONET DCS network. Ethernet traffic may bemapped into SONET containers, for example, STS and VT groups using thecapabilities of channelized framer 802 and packet mapper 806. Themapping may be transparent. In such an application, privacy is typicallyof paramount importance.

[0051] The present invention may include traffic shaping, which may besupported by the policing, shaping, flow control and subscribermanagement functionality represented by functional block 806. Thisfunctionality may allow Ethernet subscriber ports to be rate limitedwith a 1 Mbps granularity up to gigabit rate or be shut off entirely,and may permit the service provider to offer Internet access provisionedas metered, tiered or burst-able service. For example, with tieredservice the subscriber may choose a specific “capacity tier” to set themaximum allowable capacity they may access. Those limits may be setwith, for example, a 10% granularity for 10/100 Ethernet and a 5%granularity for gigabit Ethernet. An embodiment may also allow a serviceprovider to offer metered service in which subscribers pay only for thebandwidth they use on a per-use basis. In such an arrangement, the onlybandwidth limit is the port speed (10 Mbps/100 Mbps/GbE). In addition,the service provider may offer “burst-able” service, which may be viewedas a combination of tiered and metered service. With “burst-able”service the subscriber operates within a specific “bandwidth tier,”allowing the subscriber to obtain a fixed amount of bandwidth. Theallowed bandwidth limit might be set with, for example, a 10%granularity for 10 Mbps/100 Mbps Ethernet and with a 5% granularity forgigabit Ethernet service. The subscriber may then burst at up to thephysical port speed.

[0052] In addition, the policing, shaping, flow control and subscribermanagement functionality represented by block 806 may supportintelligent traffic shaping, which may guarantee minimum latency fordelay-sensitive traffic such as packet voice. The present invention mayprovide subscriber port shaping/policing capabilities configurable tosupport IP Differentiated Services Code Point (DSCP) prioritized and/orweighted queuing enabling, for example, eight different link layertraffic priority levels as per 802.1D(p). It may also reprioritize802.1D(p) priorities in the 802.1Q tag for traffic that exceeds thesubscriber's provisioned bandwidth. An embodiment of the presentinvention may issue PAUSE frames when a subscriber attempts to burstbeyond its provisioned bandwidth. However, the present invention maysupport intelligent traffic shaping that extends the PAUSE frame conceptso that only certain flows (e.g. Internet access flows) are throttled.The intelligent traffic shaping approach is in addition to DSCP and802.1D(p) priorities, because it guarantees a traffic shaping proceduregoing beyond priorities. This may provide enhanced traffic management,because priorities are irrelevant if the physical port is paused. Anembodiment of the present invention may support a policing & congestioncontrol mechanism similar to Frame Relay's Discard Eligible (DE)standard, marking traffic that is above the traffic profile and treatingsuch traffic with a higher discard probability when network congestionoccurs. Discretionary traffic shaping may be based on flow/prioritytype, and may permit traffic shaping at a physical port to be honored asmay be required by a service level agreement (SLA). For example, anembodiment in accordance with the present invention may support systemperformance characteristics that meet the standard service provider'sSLA's such as, for example, a one-way delay of 65 msec, data loss of 1%,and 100% availability. The functionality in block 806 supports thereality that some flows, however, should not be shaped. In general,Voice-over-Internet Protocol (VoIP) flows should not be paused, so thatminimum latency to the MPLS IP network can be guaranteed for voiceconnections, for example.

[0053] The functionality represented by block 806 may also permit thecollection of usage statistics based on class-of-service (CoS)/qualityof service (QoS) for network management and SLA conformance purposes.Key benchmarks in such agreements may be latency, latency variation anddata loss, and such parameters may be measured by an embodiment of thepresent invention. Other statistics that may be collected include port,VLAN, and 802.1D(p) traffic statistics, and available resources(bandwidth, buffer space, protection bandwidth, etc). An embodiment mayalso support the gathering of traffic statistics on subscriber portsindependently. This information may be reported to operating personnelor systems at a remote location by embedded microprocessor core 824,using the SONET data communications channel (DCC).

[0054] An embodiment of the present invention may protect 100% ofallocated subscriber access bandwidth to IP service within the network,and may also provide different levels of protection. In a fiber cut orport failure scenario, the traffic restoration mechanism containedwithin block 820 may use SONET UPSR ring technology for fault discovery,traffic switchover and alarm propagation. Channelized framer 802 mayhave, for example, two STS-48 ports to connect either to the ring or toa redundant backplane link. On the subscriber side, an embodiment of thepresent invention may provision protected links between itself and theCPE. Each subscriber may have, for example, two connections, and theprotected connection may switch over if the main connection goes down.Software stored in embedded memory 826 may direct embeddedmicroprocessor core 824 to use VLAN mapping to different 802.1D(p)priorities as a way to protecting subscriber traffic at different levelsof protection.

[0055] An embodiment of the present invention may support advancedmaintenance and operations support functionality, due in part to theimmediate and broad access by embedded microprocessor core 824 to statusinformation and operating parameters contained within, for example,channelized framer 802, MACs 810 and 812, packet mapper 804, DS1/DS3framers 814, 816, and 818, and policing/shaping/flow control/subscribermanagement functionality 806. To support such functionality, anembodiment of the present invention may provide for creation of asubscriber demarcation point in the same facility as the CPE, and maypermit remote loop-back at both the line and MAC levels. This capabilitymay enable the monitoring and isolation of physical problems on thesubscriber link from a remote location up to the CPE. In addition, MAC810 and MAC 812 may support time-domain-reflectometry (TDR)functionality on ports to isolate break points for copper-basedsubscriber loops. Software instructions contained within embedded memory826 or external memory connected to external memory interface 828 maypermit processor 824 to report the illustrated failure conditions,locations, and other diagnostic information to the operator of thesystem either through control frames (dedicated VLAN) or via the SONETDCC channel. An embodiment may also have the mechanisms to identify andgeographically locate network degradation using alarms from theequipment, and may be able to distinguish between layer 0/1 and layer 2degradation or faults.

[0056] An embodiment in accordance with the present invention mayinclude external memory that may be accessed by embedded microprocessorcore 824 via external memory interface 828. This functionality may allowsoftware instructions stored in embedded memory 826 or external memoryconnected to external memory interface 828 to use the SONET DCC channelfor remote management & provisioning. Software programs stored inembedded memory 826 may permit embedded microprocessor core 824 toreceive via a private Ethernet tunnel in-the-field downloadable softwareupgrades to be stored in a flash memory connected to external memoryinterface 828. It will be clear to those skilled in the art that theability to remotely upgrade software is of great value in operating andmaintaining networking equipment. In addition, the instructions for analgorithm comparable to admission control may be contained withinembedded memory 826 or external memory connected to external memoryinterface 828 and implemented by embedded microprocessor core 824, todisallow provisioning changes which would adversely affect customertraffic and/or the level of traffic protection within the network.

[0057] An embodiment of the present invention may support the logical“bonding” of lower capacity communications circuits to effectively forma link of higher capacity such as that illustrated in FIG. 8a. Bondingmay make a group of lower capacity circuits appear as a higher capacitypath, by spreading or “inverse multiplexing” the source traffic on thehigher capacity link over the lower capacity circuits belonging to thebonded group of circuits. At the other end of the bonded segment, thetraffic on each of the lower capacity circuits may be merged into ahigher capacity link, or it may be carried over another bonded group ofcircuits of different types or capacities. The provisioning informationneeded to identify the lower speed circuits to be bonded may be providedeither at the equipment site, or from a remote location.

[0058]FIG. 8a shows an exemplary embodiment illustrating the bonding ofseven DS1 synchronous time division multiplex circuits into a bondedgroup 830 a that transports the traffic from 10 Mbps Ethernet link 805 ato 10 Mbps Ethernet link 815 a, in accordance with the presentinvention. Although the illustration shows seven DS1 circuits bonded fortransport of a single 10 Mbps Ethernet packet link, lower-speed circuitsother than DS1 may be used to transport traffic from higher-speednetwork connections without departing from the spirit of the invention.In FIG. 8a, a group of circuits are bonded as a transport mechanism byidentifying to Ethernet/TDM bonding function 810 a and 820 a thecircuits in the group, and the packet interface to which they connect.Ethernet/TDM bonding function 810 a and 820 a may be implemented by thefunctionality shown in FIG. 8b. An algorithm may be implemented withinhashing processor 838 b of FIG. 8b, located at a first location,allowing it to cooperate with a distant hashing processor 838 b, locatedat a second location, to “bond” or aggregate the communications circuitssuch as those in bonded group 830 a of FIG. 8a, which connect the twolocations. The communication circuits within bonded group 830 a may be,for example, communication circuits such as those shown in FIG. 8b astrunk-side DS1 circuits 846 b connected to DS1 framer 819 b. In theexemplary embodiment, hashing processor 838 b determines which of thelower speed circuits contained in bonded group 830 a should be used tocarry the next of the packets received from the higher speed link. Thealgorithm used by hashing processor 838 b in selecting the circuitwithin bonded group 830 a to be used to transport a given packet maytake into consideration, among other things, the size of the packet, thepriority of the packet, the allowable latency or maximum delay allowedin getting the packet to its destination, and the occupancy of each ofthe lower speed circuits in bonded group 830 a. Information from thepolicing/shaping/flow-control/subscriber-management block 806 b, MACs810 b and 812 b, VLAN engine 808 b, and embedded memory 826 b may beused by hashing processor 838 b and embedded microprocessor core 824 bin the management of bonded group 830 a. Performance measurements anddiagnostic information regarding the operation of bonded group 830 a maybe gathered and distributed by embedded microprocessor core 824 b.

[0059] An embodiment of the present invention may also include an M13multiplexer (mux), which is illustrated as block 844 b in FIG. 8b. M13mux 844 b may be used to combine a number of DS1/E1 streams from DS1/E1framer 814 b into a single DS3/E3 stream transported via DS3/E3 framer816 b. The DS3/E3 stream may be switched to channelized framer 802 b fortransport via optical link 834 b, or it may be carried on a DS3/E3trunk. This permits voice traffic from multiple DS1/E1 circuits to becarried via one DS3/E3 link. Management and monitoring of the operationof M13 mux 844 b may be provided by embedded microprocessor core 824 bexecuting program instructions stored in embedded memory 826 b.Performance and diagnostic information may be provided either locally,or remotely via a dedicated VLAN connection or the SONET DCC.

[0060] Another embodiment in accordance with the present invention mayinclude system packet interface (SPI) 840 b of FIG. 8b, to permitexpansion of the packet network interface capacity. System packetinterface 840 b is not required for operation of an embodiment of thepresent invention, but may be incorporated if MACs 810 b and 812 b donot provide sufficient packet interface capacity for a particularapplication of the invention.

[0061]FIG. 9 is a high-level flow diagram of a method of operating anembodiment of the present invention. In such an embodiment, the incomingSONET data stream is received (block 902) from a synchronous opticalnetwork, for example, and converted into a packet formatted stream(block 904). The packet stream is then transmitted (block 906) to anEthernet packet network, for example. In the reverse direction, anincoming packet stream is received (block 908) from an Ethernet packetnetwork, for example, and converted to a SONET compatible format (block910). The resulting SONET data stream is then transmitted (block 912) toa synchronous optical network, for example.

[0062]FIG. 9a shows a high-level flow diagram illustrating a method ofoperating another embodiment in accordance with the present invention.The blocks shown in FIG. 9a represent the functions that are performedby blocks 810 a and 820 a as shown in FIG. 8a. In the exemplaryembodiment, the contents of a packet received from a designated packetinterface (block 908 a) is converted to a stream of data (block 910 a)for transmission over a lower-speed communications circuit selected fromthe bonded group of circuits for the designated packet interface (block912 a). The particular circuit to be used may be selected from thebonded group based upon, for example, the amount of data containedwithin the packet, the amount of data remaining to be transmitted oneach of the circuits in the bonded group, the delay requirements of thesubscriber being served by the packet interface, the priority of thepacket, or one of a number of other criteria. Once the circuit has beenselected, the stream of data is transmitted on the selected lower-speedcircuit (block 914 a) to the far end of the bonded group.

[0063] At the far end of the bonded group, the data is received from thelower-speed communications circuit (block 902 a) and converted to packetformat (block 904 a). The formatted packet is then transmitted on thehigher-speed packet interface that has been designated for use with thebonded group of lower-speed communications circuits (block 906 a). Thebonded group of lower speed communications circuits might be, forexample, seven DS1 time division multiplex connections each operating at1.544 Mbps, while the packet interface may be a 10 Mbps IEEE 802.3Ethernet compliant connection.

[0064]FIG. 9b illustrates a network architecture in which, for example,two bonded groups are used in sequence, in accordance with oneembodiment of the present invention. In FIG. 9b, packet traffic onEthernet link 905 b is transferred by Ethernet/DSL bonding function 910b to a bonded group of digital subscriber lines (DSL) 930 b. Bondedgroup 930 b connects to DSL/DS1 conversion function 915 b, whichtransfers the data from the circuits of bonded group 930 b to bondedgroup 940 b made of DS1 circuits. The data from bonded group 940 b isthen converted back to Ethernet packet format and transmitted onEthernet link 925 b by DS1/Ethernet bonding functionality 920 b.

[0065]FIG. 9c shows an example network architecture using, for example,multiple embodiments 910 c, 915 c, and 920 c of the present invention tointerface a packet link to a SONET optical link. In FIG. 9c, an Ethernetpacket link is carried over two successive bonded groups for eventualtransport over a SONET optical link. Ethernet/DSL bonding function 910 cconnects Ethernet packet link 905 c to a bonded group of DSL links 930c. Data traffic on bonded group 930 c is then transferred to a bondedgroup of DS1 circuits 940 c by DSL/DS1 conversion function 915 c. Bondedgroup 940 c is then mapped for transport via a SONET or SDH optical linkby DS1/SONET mapping function 920 c. Although the embodiments describedreference specific packet and circuit standards, speeds, and parameters,the present invention is not so limited and can be applied in yetfurther embodiments without departing from the spirit of the invention.

[0066]FIG. 10 is a high-level flow diagram of a further method ofoperating an embodiment according to the present invention. In such anembodiment, embedded microprocessor core 824 of FIG. 8, or 824 b of FIG.8b may collect operational statistics from, for example, the SONETreceive processing (block 1002), the SONET transmit processing (block1004), the packet receive processing (block 1006), and the packettransmit processing (block 1008) functional blocks. It may also gatherstatistics regarding the operation of hashing processor 838 b of FIG.8b. The gathered statistics may then be analyzed (block 1010) andembedded microprocessor core 824 or 824 b may then determine, theactions or adjustments that may be needed for desired system operation.Embedded microprocessor core 824 or 824 b may then adjust the operation(block 1012) of the functional blocks in the embodiment, and may reporttroubles and performance (block 1014) to a predetermined location. Manyimprovements in the level of diagnostics, performance, and controlbecome available by closely integrating the functionality shown in FIG.7 in the form of, for example, a single chip or multi-chip embodiment.

[0067] Accordingly, the present invention may be realized in hardware,software, or a combination of hardware and software. The presentinvention may be realized in a centralized fashion in one computersystem, or in a distributed fashion where different elements are spreadacross several interconnected computer systems. Any kind of computersystem or other apparatus adapted for carrying out the methods describedherein is suited. A typical combination of hardware and software may bea general-purpose computer system with a computer program that, whenbeing loaded and executed, controls the computer system such that itcarries out the methods described herein.

[0068] The present invention also may be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

[0069] Notwithstanding, the invention and its inventive arrangementsdisclosed herein may be embodied in other forms without departing fromthe spirit or essential attributes thereof. Accordingly, referenceshould be made to the following claims, rather than to the foregoingspecification, as indicating the scope of the invention. In this regard,the description above is intended by way of example only and is notintended to limit the present invention in any way, except as set forthin the following claims.

[0070] While the present invention has been described with reference tocertain embodiments, it will be understood by those skilled in the artthat various changes may be made and equivalents may be substitutedwithout departing from the scope of the present invention. In addition,many modifications may be made to adapt a particular situation ormaterial to the teachings of the present invention without departingfrom its scope. Therefore, it is intended that the present invention notbe limited to the particular embodiment disclosed, but that the presentinvention will include all embodiments falling within the scope of theappended claims.

What is claimed is:
 1. A data communications device comprising: ahashing processor for selecting a transmit data channel and fordesignating a receive packet interface and a transmit packet interface;a packet mapper for processing at least one transmit packet from thedesignated transmit packet interface operating at a first bit rate, thepacket mapper transferring the contents of the at least one transmitpacket to the selected transmit data channel, the packet mapper also forprocessing data from at least one receive data channel producing atleast one receive packet for transmission on the designated receivepacket interface operating at the first bit rate; and at least onecommunication interface for serializing data from the transmit datachannel to form a transmit data stream, and for passing to the receivedata channel deserialized data from a receive data stream, the transmitdata stream and receive data stream operating at a second bit rate. 2.The data communications device of claim 1 wherein the first bit rate isgreater than the second bit rate.
 3. The data communication device ofclaim 1 wherein a packet format of the at least one receive packet andthe at least one transmit packet is compliant with at least one of theInstitute of Electrical and Electronic Engineers 802.3 family ofEthernet standards.
 4. The data communications device of claim 1 furthercomprising at least one optical carrier framer for performing transmitframing on data from at least one transmit data channel producing atransmit data sequence, and for performing receive framing on a receivedata sequence producing data for at least one receive data channel. 5.The data communication device of claim 4 wherein the packet mapper iscompatible with the American National Standards Institute T1X1.5 GenericFraming Procedure.
 6. The data communication device of claim 4 whereinthe packet mapper is compatible with the InternationalTelecommunications Union X.86 Ethernet over SONET recommendation.
 7. Thedata communication device of claim 4 wherein the packet mapper iscompatible with the Internet Engineering Task Force RFC 1662point-to-point protocol specification.
 8. The data communications deviceof claim 4, wherein a format of the transmit data sequence and thereceive data sequence is compatible with the Synchronous Optical Networkor Synchronous Digital Hierarchy optical carrier standard.
 9. The datacommunication device of claim 1 further comprising a bus interface forconnecting additional communications interface devices.
 10. The datacommunication device of claim 9, wherein the bus interface is a telecombus compatible interface.
 11. The data communication device claim 1wherein the at least one communication interface comprises at least oneT/E carrier framer for receiving and transmitting data in time divisionmultiplexed format.
 12. The data communication device of claim 11wherein the at least one T/E carrier framer comprises a DS1 or E1 formatframer.
 13. The data communication device of claim 11 wherein the atleast one T/E carrier framer comprises a DS3 or E3 format framer. 14.The data communication device of claim 12 further comprising a M13multiplexer for converting DS1 format time division multiplex datastreams to and from DS3 format.
 15. The data communication device ofclaim 1 further comprising at least one embedded microprocessor corearranged in order receive signals from the hashing processor.
 16. Thedata communication device of claim 15, further comprising an embeddedmemory for storing information to be accessed by the at least oneembedded microprocessor core.
 17. The data communication device of claim15 further comprising an external memory interface arranged to allow theat least one embedded microprocessor core to access information storedin an external memory device.
 18. The data communication device of claim1 wherein the functionality is contained within a single integratedcircuit.
 19. A method of operating a data communication device, themethod comprising: receiving a first packet from a first packet streamat a higher bit rate; selecting a first data link from a predefinedgroup of data links; depacketizing the first packet to a first datastream; transmitting the first data stream on the first data link at alower bit rate; receiving a second data stream on a second data link atthe lower bit rate; packetizing the second data stream into a secondpacket; designating a second packet stream on which to send the secondpacket; and transmitting the second packet on the second packet streamat the higher bit rate.
 20. The method of claim 19 wherein a packetformat of the first packet stream and the second packet stream iscompliant with at least one of the Institute of Electrical andElectronic Engineers 802.3 family of Ethernet standards.
 21. The methodof claim 19 wherein the first data link and the second data link use atime division multiplex format.
 22. The method of claim 21 wherein thetime division multiplex format is DS1 or E1 compliant.
 23. The method ofclaim 19 wherein the first data link and the second data link are a typeof digital subscriber line.
 24. A machine-readable storage, havingstored thereon a computer program having a plurality of code sectionsfor implementing a data communication device, the code sectionsexecutable by a machine for causing the machine to perform theoperations comprising: receiving a first packet from a first packetstream at a higher bit rate; selecting a first data link from apredefined group of data links; depacketizing the first packet to afirst data stream; transmitting the first data stream on the first datalink at a lower bit rate; receiving a second data stream on a seconddata link at the lower bit rate; packetizing the second data stream intoa second packet; designating a second packet stream on which to send thesecond packet; and transmitting the second packet on the second packetstream at the higher bit rate.
 25. The machine-readable storage of claim24 wherein a packet format of the first packet stream and the secondpacket stream is compliant with at least one of the Institute ofElectrical and Electronic Engineers 802.3 family of Ethernet standards.26. The machine-readable storage of claim 24 wherein the first data linkand the second data link use a time division multiplex format.
 27. Themachine-readable storage of claim 26 wherein the time division multiplexformat is DS1 or E1 compliant.
 28. The machine-readable storage of claim24 wherein the first data link and the second data link are a type ofdigital subscriber line.